Methods and apparati for transformation of a sequence of video images in real time tend to fall in two classes of approaches. The word "video", as used herein, is intended to refer to any electronic display of text and/or graphics images and is not intended to be limited to the standard television images presented at 50--60 frames per second. First are hardware-intensive approaches that provide a limited number of transformations of a sequence of live video images "on the fly". These transformations include translation, rotation, compression, and variations in compression across an image to simulate curved effects. These approaches often make use of specialized hardware for pixel data filtering and interpolation to carry out any of these real time transformations. Examples of transformation apparati that incorporate these filtering and interpolation techniques are discussed in U.S. Pat. No. 4,665,433, issued to Hinson et. al., and in U.S. Pat. No. 4,760,605, issued to David et. al.
Another class of methods and associated apparati perform the video image transformations off-line and in non-real time. A video transformation mapping is applied to each of a sequence of single video images, and these mapped images are stored on a suitable video medium such as video tape. The stored images may then be called from storage and played back in real time to view the effect of this transformation. Because these video transformation mappings are not restricted to real time, the number and complexity of the allowable transformations is virtually unrestricted. Some of the transformations that may be applied here include intensity, high-light, true overlapping curvatures in three-dimensional space and metamorphosis. This will be referred to as the "off-line, non-real time" approach. The associated apparati are usually simpler, less expensive and software-intensive, but the off-line time required to perform a sequence of such transformations is often measured in hours or tens of hours. Additionally, if a video transformation mapping is applied using a new series of video images, the time consuming mapping of each image in the series must again be done before the effect can be viewed.
What is needed is a method and associated apparatus that will permit performance of a class of predetermined sequences of mappings or transformations upon an arbitrary sequence of video images in real time, which are as complex as the mappings permitted under the off-line approach described above. Preferably, the intermediate video transformation mappings should be storable in a memory of reasonable size, and each sequence of such video image transformation mappings should be retrievable quickly by selection of an indicium that is associated with that sequence of transformations.